Description: (verbatim from the applicant's abstract) Membranes and the proteins embedded within them compartmentalize specialized machinery that provides the means by which cells and organelles communicate, generate energy, take up nutrients, excrete wastes, transduce signals by transporting metabolites between internal compartments, and build gradients of ions (and other small molecules) which are used to fuel all normal cellular activities in healthy organisms. Structural information for membrane proteins is exceedingly scarce - it is notoriously difficult to purify quantities of native material that are sufficient for crystallization attempts. Today's methods for the overproduction of protein cannot deal with membrane proteins, thus this important class is virtually ignored. In order for significant advances to be made, innovative strategies are needed rather than incremental advances in existing technology. We have exploited the unique physiology of the Rhodobacter species of photosynthetic bacteria to overexpress heterologous proteins, and have recently shown that a human outer membrane protein is expressed and incorporated into induced membranes of this organism. We now propose to develop this system to be a general one for the expression of functional membrane proteins - from any organism - in quantities that are sufficient for biochemical studies and crystallization trials for structure determination.